By Rachael Rettner, Senior Writer
Published: 02/10/2014 04:44 PM EST on LiveScience
People should be cautious about using two new weight-loss drugs because it's not clear whether they increase the risk for heart problems, some doctors argue.
In 2012, the Food and Drug Administration approved two weight-loss drugs: lorcaserin hydrochloride (brand name Belviq, manufactured by Eisai Inc.) and phentermine-topiramate (brand name Qsymia, manufactured by Vivus, Inc.).
While these drugs are moderately effective at helping people lose weight, they can cause serious side effects, including memory and attention problems, and increased acid in the body fluids, according to a new editorial published in the Feb. 10 issue of the journal JAMA Internal Medicine. [Dieters, Beware: 9 Myths That Can Make You Fat]
What's more, studies could not rule out the possibility that the drugs increase the risk of heart disease and other cardiovascular problems, the editorial said. The drugs have raised concerns about heart safety because phentermine is known to increase heart rate, and previous weight-loss drugs were removed from the market because of their association with heart problems, including heart attacks and strokes.
"In our view, approving the drugs for marketing without more definitive evidence [of heart safety] is an unnecessary gamble," wrote the editorial authors Dr. Steven Woloshin and Dr. Lisa M. Schwartz, of the Dartmouth Institute for Health Policy and Clinical Practice, who noted that the drugs have not been approved in Europe, because of concerns over heart risks.
The authors say it would be better to rule heart risks before approval "rather than approve the drug and expose a lot of people to it while sorting it out," Woloshin told Live Science.
"Until there is more convincing evidence about the cardiovascular safety of these drugs, physicians and patients should approach them cautiously," the authors said. Patients who do not lose at least 5 percent of their body weight within 12 weeks of starting the drug should stop taking it, because they are unlikely to benefit from the drug, the authors said.
In studies conducted before the drugs were approved, patients taking lorcaserin for a year lost 3 percent more of their body weight than did those taking a placebo, and patients taking phentermine lost 7 percent more of their body weight. The FDA approved the drugs on the condition that their makers conduct studies looking into the drugs' heart risks. Waiting until such studies were completed to approve the drugs would "delay effective therapy" for obesity, the FDA said.
Although obesity treatments are limited, Woloshin and Schwartz said they disagree with the FDA's decision to approve these weight-loss drugs so rapidly.
The harmful consequences of obesity develop over many many years, Woloshin said. "The problems don't seem acute enough to require rushing the approval of new drugs," Woloshin said.
The authors also noted that studies have not looked at whether these weight-loss drugs reduce a person's overall risk of dying or developing other chronic diseases.
And the additional studies requested by the FDA appear to be behind schedule: there is no evidence that protocols for the studies have been submitted, even though this submission was required eight to 16 months ago, the editorial said.
"Even if they were done on time, the studies weren’t planned to be finished until four or five years from now," Woloshin said. That means "there's a really long time when these questions will be open," Woloshin said.
Until those studies are completed, the authors recommend that the FDA change the labels of these weight-loss drugs, to make clear that there are concerns about the drugs' heart risks, the editorial said.